4) So far, we have looked at finding cell potentials under standard conditions, however in reality, we are seldom at standard conditions. Recall that our equation for the Gibbs free energy at nonstandard conditions was AG=AG+RTINQ By substituting -nFE for G in the above equation we come to the Nernst equation (shown below), which gives a way to predict E under any conditions, not just standard conditions. In this equation, R is the gas constant (8.314 J mol K). F is the Faraday Constant (96480 C mol) and Q is the reaction quotient. RT E=E no cell The Nemst equation is extremely powerful, and can be written in a slightly more useful form. First, the natural log (In) can be replaced by log base 10 (log) by multiplying by 2.3 (InQ = 2.3logQ), and we can rearrange terms to put the equation into the form of a straight line, as shown. El 2.3RT nFlogQ+ Ecell a) Consider this form of the Nernst equation, sketch a plot of E. vs logQ. b) Notice that the term "-(2.3*RT/nF)" is made up entirely of constants except for "n". Solve for the value of this at 298 K, you may leave "n" as a variable. c) How does the 'term' in part b, correspond to the plot you drew in part a?

4) So far, we have looked at finding cell potentials under standard conditions, however in reality, we are seldom at standard conditions. Recall that our equation for the Gibbs free energy at nonstandard conditions was AG=AG+RTINQ By substituting -nFE for G in the above equation we come to the Nernst equation (shown below), which gives a way to predict E under any conditions, not just standard conditions. In this equation, R is the gas constant (8.314 J mol K). F is the Faraday Constant (96480 C mol) and Q is the reaction quotient. RT E=E no cell The Nemst equation is extremely powerful, and can be written in a slightly more useful form. First, the natural log (In) can be replaced by log base 10 (log) by multiplying by 2.3 (InQ = 2.3logQ), and we can rearrange terms to put the equation into the form of a straight line, as shown. El 2.3RT nFlogQ+ Ecell a) Consider this form of the Nernst equation, sketch a plot of E. vs logQ. b) Notice that the term "-(2.3*RT/nF)" is made up entirely of constants except for "n". Solve for the value of this at 298 K, you may leave "n" as a variable. c) How does the 'term' in part b, correspond to the plot you drew in part a?

Chemistry

10th Edition

ISBN:9781305957404

Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Chapter1: Chemical Foundations

Section: Chapter Questions

Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...

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A student made measurements on some electrochemical cells and calculated three quantities: • The standard reaction free energy AG. The equilibrium constant K at 25:0 °C. The cell potential under standard conditions E His results are listed below. Unfortunately, the student may have made some mistakes. Examine his results carefully and tick the box next to the incorrect quantity in each row, if any. Note: If there is a mistake in a row, only one of the three quantities listed is wrong. Also, you may assume the number of significant digits in each quantity is correct.. Also note: for each cell, the number n of electrons transferred per redox reaction is 2. cell n A B C 2 2. 2 calculated quantities. (Check the box next to any that are wrong.) .0 AG 172. kJ/mol J 127. kJ/mol - 170. kJ/mol K -31 7.36 X 10 5:63 X.10 - 23 29 6.06 × 10 - O O E -0.89 V. 0:66 V -0.88. V 5
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A student made measurements on some electrochemical cells and calculated three quantities: • The standard reaction free energy AG". • The equilibrium constant K at 25.0 °C. • The cell potential under standard conditions E. His results are listed below. Unfortunately, the student may have made some mistakes. Examine his results carefully and tick the box next to the incorrect quantity in each row, if any. Note: If there is a mistake in a row, only one of the three quantities listed is wrong. Also, you may assume the number of significant digits in each quantity is correct. Also note: for each cell, the number n of electrons transferred per redox reaction is 1. calculated quantities (Check the box next to any that are wrong.) cell n 46° K 1 - 124. kJ/mol 5.30 x 10 21 -1.28 V -18 4.53 x 10 B 1 - 99. kJ/mol -1.03 V -7 2.20 x 10 1 - 38. kJ/mol 0.39 V
For the cell shown, the measured cell potential, Ecell, is −0.3627 V at 25 °C. Pt(s) | H2(g,0.735 atm) | H+(aq,? M) || Cd2+(aq,1.00 M) | Cd(s) The balanced reduction half-reactions for the cell, and their respective standard reduction potential values, ?o, are 2H+(aq)+2e−⟶H2(g) ?o=0.00 V Cd2+(aq)+2e−⟶Cd(s) ?o=−0.403 V Calculate the H+ concentration in M.
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